1. Field of the Invention
This invention relates to a combine harvester comprising a housing and a concave, which is disposed in the housing below a threshing drum and comprises a frame that is rotatably mounted in the housing and a insert which is detachably mounted in the frame.
2. Description of the Prior Art
For an adaptation of the thresher of a combine harvester to a given crop to be harvested, the speed of the threshing drum and the clearance between the concave and the threshing drum must be adjusted and the mesh size of the concave must also be selected in view of the crop to be harvested. For that purpose the concave must be removed and replaced by a concave having a different mesh size. In known combine harvesters the concave can be removed only with difficulty because it is necessary to remove the shaker and the cleaning sieve before the concave is accessible and said operations involve a substantial working time.
To permit the concave to be replaced without a need for changing the holder for the concave and the means for adjusting the concave, it is known from German Patent Specification No. 720,503 to provide a concave which is composed of a frame that is rotatably mounted in the housing and an insert, which can slidably be inserted into lateral guide rails of the frame in the peripheral direction of the threshing drum, transversely to the axis of the drum, and can be fixed in position by means of set screws. In that case an alteration of the combine harvester requires only the insert rather than the entire concave to be replaced. But even in that case the shaker and the cleaning sieve must also be removed in order to render the concave accessible for a replacement of its insert.